RE: RE: Formula for percentage arcs anyone? from ykleetx_at_gmail.com on 2013-09-04 ([Indoor

From: <ykleetx_at_gmail.com>
Date: 04 Sep 2013 09:59:33 -0700

Thank you, John!

--- In Indoor_Construction@yahoogroups.com, <indoor_construction@yahoogroups.com> wrote:

Mike,

Don has shown how to do the arc in Autocad but if you want a formula to solve the problem then one can be written from the geometry of intersecting chords and I give it below.

Radius of Arc = 0.5(C^2/4h + h) where C is the chord of the arc and h is the height at the centre of the camber.

Example: A 6” chord with a 5% camber height at the centre.

Then camber height, h = 0.05 x 6 = 0.3”.

Radius = 0.5(6^2/(4 x 0.3) + 0.3) = 15.15”.

John Barker - England

From: Indoor_Construction@yahoogroups.com [mailto:Indoor_Construction@yahoogroups.com] On Behalf Of mkirda@...
Sent: 04 September 2013 05:04
To: Indoor_Construction@yahoogroups.com
Subject: [Indoor_Construction] Formula for percentage arcs anyone?

Greetings.

I am trying to reproduce a 5% airfoil in AutoCAD and I'm not having a lot of luck. Everything seems to default to degree arcs, which isn't a problem, however I cannot find a formula to convert between the two.

Anyone have the formula handy?

Regards.
Mike Kirda

Received on Wed Sep 04 2013 - 09:59:33 CEST